Corbin Russwin ML20906 ASB 626 SAF Electrically Controlled Mortise Lock - Fail Safe - ASB Lever - Satin Chrome

The Corbin Russwin ML20906 SAF is the fail safe function in the ML20900 ECL (Electrically Controlled Lock) series: when the access control panel energizes the lock, the outside lever locks. When the panel removes power or when power fails for any reason, the outside lever unlocks automatically and the door operates freely. This makes the ML20906 SAF the correct specification for fire-rated egress doors, corridors in hospitals and schools where code requires unlocked egress during fire alarm activation, and any opening where life safety code prohibits a locked door on power failure.

When the lock is energized and the outside lever is locked, a key in the outside cylinder still retracts the latch bolt. The cylinder override is mechanical and independent of the electrical function. Inside lever is always free at all times regardless of electrical state. Auxiliary latch deadlocks the main latch bolt when the door closes. For all electrified mortise locks and access control hardware, browse our Corbin Russwin lever locks catalog and our electronic hardware catalog.

Fail Safe vs. Fail Secure: The Critical Specification Decision

The ML20906 SAF is fail safe: power on equals locked, power off equals unlocked. The ML20900 SEC is fail secure: power on equals unlocked, power off equals locked. These two behaviors are not interchangeable and the specification must match code requirements for the specific opening before ordering.

Fail safe (SAF) is required where life safety code mandates free egress during emergencies. Fire alarm activation typically cuts power to fail-safe locks via the building fire control panel, automatically releasing the door for evacuation. Fail safe is the standard specification for fire-rated corridors, hospital egress routes, and any AHJ-required free-egress opening.

Fail secure is appropriate for access-controlled openings where the door must remain locked during a power failure: server rooms, pharmacies, secure storage, and controlled access areas where an unlocked door during a power event creates a security or liability problem.

Corbin Russwin ML20906 NSA SAF Technical Specifications

Series: Corbin Russwin ML20900 ECL. Function: SAF, Fail Safe, Single Cylinder. Outside grip behavior: locked when energized (power on); unlocked when de-energized (power off). Cylinder override: yes, key retracts latchbolt from outside even when lock is energized. Inside grip: always free regardless of electrical state. Auxiliary latchbolt: deadlocks latchbolt when door closes. Trim: NSA, NS Lever (Newport), A Rose, 626 Satin Chrome. Voltage: 12/24 VDC. Continuous current draw: 15mA. Peak current draw: 0.5A maximum; maximum 2 locks per 1A power supply. Monitor switch rating: 2A at 24VDC. Operating voltage tolerance: not to exceed +/- 10%. Door thickness: 1-3/4" (44mm) standard. Backset: 2-3/4" (70mm). Handing: quick reversible without disassembling lock case. Lockcase: heavy-gauge chrome plated steel, 5-7/8" x 4" x 15/16". Latchbolt: 2-piece with anti-friction insert, 5/8" x 1" x 3/4" throw (19mm). Auxiliary latchbolt: 9/16" effective throw, 3/8" effective deadlocking. Strike: ANSI straight lip, 4-7/8" x 1-1/4" x 1-1/8" lip to center. Cylinder: 6-pin, L4 keyway standard; 7-pin optional; IC available. Keys: two nickel silver standard. Keying: KD standard; Keyed Alike (+$20); Master Keyed (+$30); Construction Master Keying. Warranty: 10-year limited.

Monitor Options: M91 and M92

Two SPDT monitor switch options are available and can be added at time of order.

M91 is the latchbolt monitor. It's a SPDT switch that monitors full extension of the main latch bolt. When the latch is fully extended (door closed and latched), the switch signals the access control panel. When the latch retracts (door opened or latch pressed), the switch changes state. M91 provides door position monitoring without a separate door position switch.

M92 is the Request-to-Exit (REX) monitor. It's a SPDT switch that activates when either lever is operated from either side. When the inside lever is turned for egress, the REX switch signals the access control panel to shunt the door alarm and log the exit event. M92 allows the access control system to differentiate between authorized egress and forced door events at the same opening.